This invention relates to a device for supporting cops in a circular knitting machine, particularly in fixed needle cylinder knitting machines.
Known are devices for supporting cops in circular knitting machines, which comprise in general one or more frames associated above the machine to enable the several yarns to run down to the machine feeds.
Such devices are, especially in the instance of multi-feed large diameter machines, of considerable size and positioned at such an elevation as not to interfere with the machine parts at work and any operators busy near the machine.
This forces the operator in charge of cop doffing and checking to equip himself with a ladder or the like in order to reach the frame located upwardly of the machine.
In an attempt to solve this problem, vertically movable frames have been provided which can move far down from the working position and allow a floor-based operator to get easily at the cops.
Devices of this kind may comprise a single frame of substantially loop-like configuration which is allowed to slide along one or more upright guides, or a plurality of frames laid side-by-side around the machine axis and being allowed to slide individually along one or more upright guides fast with the machine structure.
These movable type devices, while being more efficient than the stationary types, have some problems.
In order to bring the cops down to the level of the machine outer skirt, it is, in fact, necessary to arrange for the inside diameter of the loop frame to be larger than the combined dimension of the skirt diameter plus the bulk of the devices associated therewith.
Where a plurality of frames are provided, likewise the cop holders must be placed far away from the machine axis.
This requirement leads to concentrating the device weight at a zone positioned at a greater distance from the machine axis than in case of devices fixedly arranged above the machine.
This fact interferes with the application of such devices to large diameter fixed cylinder machines, where, as is known, the cop holder device rotates together with the machine skirt.
Owing to the high rotational speeds attained by modern knitting machines, centrifugal forces are brought into play which, in that condition, would pose problems of strength and stability of the structure and of anchoring the cops thereto.
Furthermore, the presence of upright guides near the skirt would create problems of space due to the presence in that area of fixed control devices which interact with the skirt.
Lowering of the frame or frames, moreover, results with such prior designs in the yarn relaxing at the several feeds, which makes it necessary to adopt yarn tensioning devices to prevent the yarn from becoming entangled and later on, as the frame moves up or the machine is started, broken, bringing the machine to a standstill.